Nowadays, using a compressor in the heating-exchanging system is essential in modern life. Compressor-manufacturers are often concerned on how to control high power compressor for the sake of extending the life of span and saving energy thereof.
For example, most of the centrifugal compressors using in central air conditioning utilize centrifugal chillers, that own large refrigerating effect for chilling large space like office building, factory, hotel and indoor stadium etc. The chilled water is cooled via evaporators and transmits the heat to the liquid refrigerant. The liquid refrigerant would become gaseous state after absorbing the heat. The gaseous refrigerant is compressed by the compressor and then transported to the condenser to engage heating-exchanging. Finally, the liquid refrigerant absorbs the heat from the chilled water. The chilled water is re-circulated back to the chiller to be cooled again.
Most of the controlling systems are for the chiller of central air conditioning, but the controlling systems have simpler controlling methods, such as redesigning the structure of the compressor (U.S. Pat. No. 5,145,317) or adjusting the rotor speed of the compressor (WO0244632). Moreover, the chiller of central air conditioning is gradually replaced by air conditioning only using the refrigerant for heating-exchanging without cooled water. Using the centrifugal compressor and the refrigerant in air conditioning has a problem regarding how to save energy and to prevent surge and exchange the heat at higher loading situation. Because manufacturers only incline to have concerns about the technique controlling the compressor but neglect that the technique shall be correspondingly adjusted with respect to different circumstances, the integrated controlling method is needed to be provided.
Accordingly, a method and a system for controlling a compressor to solve the above-mentioned problems are developed. The inventors purpose to rectify those drawbacks and provide the method and the system for controlling the compressor that control the flow rate based on the needs of the system to make the compressor and the heating-exchanging system prevent surge and save energy.